Placing fliers and door hangers

I'd like to get out and do a little advertising by going to several neighbor hoods and thought about going door to door placing door hangers. I was wondering about if you guys did that because I don't wanna make someone mad by "trespassing". That definitely won't get you any jobs. Would placing a flier on the mail box be better?

I place thousands of door hangers every spring never had anyone yell at me for trespassing. Just be good about it don't walk through their flower beds try to stick to sidewalks as much as possible. IF they yell apologize and move on.

It is defiantly illegal, i doubt anyone would ever say anything but my thought is if its in the mail it can quickly get tossed with the rest of the junk mail. If its on the door they atleast have soley that from the front door to the trash can to look at. Think about what u do with ur mail if its not a bill it gets tossed without a second look, something on your door might take couple seconds to read over it. Just my thoughts